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Emergency Oxygen

for Scuba Diving

Injuries

STUDENT HANDBOOK

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Emergency Oxygen forScuba Diving Injuries

Student HandbookDivers Alert Network6 West Colony PlaceDurham, NC 27705

DAN Education: +1-919-684-2948, ext. 555

Fax: +1-919-493-3456

Email: [email protected]

DAN Emergency Hotline: +1-919-684-9111

Membership Information: 1-800-446-2671

Authors: Nicholas Bird, M.D.; Matias Nochetto, M.D.

Editors: Nicholas Bird, M.D.; Matias Nochetto, M.D.;Eric Douglas; Neal Pollock, Ph.D.; Patty Seery, MHS, DMT

Photos: Eric DouglasLayout: Rick Melvin

Original Authors: Dan Orr, M.S. and Jerey J. Bertsch

DAN would also like to thank all those individuals that assisted in the development,creation and testing o the training materials or this program.

This program is intended or anyone who might come in contact with divers or diving-related injuries. It meets the current guidelines rom the U.S. Occupational Saety and HealthAdministration (OSHA) and the October 2010 Guidelines or Resuscitation issued by theInternational Liaison Council on Resuscitation (ILCOR)/American Heart Association (AHA).

7th Edition, March 2012

2012 Divers Alert Network

All rights reserved. No part o this publication may be reproduced, stored in a retrieval system or transmitted,in any orm or by any means, electronic, mechanical, photocopying, or otherwise without prior written permissiono Divers Alert Network, 6 West Colony Place, Durham, N.C. 27705.

Sixth edition published May 2006, fth edition published September 2002, ourth edition published February 1997,third edition published November 1994, second edition published April 1994 and frst edition published November 1993.

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DAN Emergency Oxygen for Scuba Diving Injuries2

Scuba diving injuries are rare and are oten subtle when they occur. In the unlikely event

o an injury, being able to recognize the problem and initiate appropriate action can speedthe divers recovery and minimize lasting eects. Oxygen frst aid is the frst response ordiving injuries.

The DAN Emergency Oxygen or Scuba Diving Injuries course is an entry level trainingprogram that teaches participants common presentations o dive injuries and how toprovide emergency oxygen frst aid.

During this course, participants will become amiliar with the signs and symptomsassociated with decompression illness and nonatal drowning and the proper administration

o supplemental oxygen. Proper assembly, disassembly and use o all component partsound in the DAN Oxygen Unit are included in the skills section o this course.

The DAN Emergency Oxygen or Scuba Diving Injuries student handbook introducesmedical terms that may be unamiliar to some readers. Familiarity with basic medicalterminology will enhance the quality o communication with emergency and health-careworkers. A glossary o terms is provided in the back o this handbook.

Successul completion o the DAN Emergency Oxygen or Scuba Diving Injuries courseincludes demonstration o skill competency and passing a written knowledge assessment.The result is certifcation as a DAN Oxygen Provider.

Reading this handbook without instruction and practice will not make someonecompetent to use oxygen in a diving emergency.

Find An Instructor

www.DAN.org/training/directory/default.aspx

Find an Industry Partner

www.DAN.org/partner/directory/

DAN

Emergency

Oxygen for

Scuba DivingInjuries

Course Overview1
http://www.dan.org/training/directory/default.aspxhttp://www.dan.org/partner/directory/http://www.dan.org/partner/directory/http://www.dan.org/training/directory/default.aspx

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3DAN Emergency Oxygen for Scuba Diving Injuries

Emergency-response skills deteriorate with time. Retraining is required every two yearsto maintain DAN Emergency Oxygen or Scuba Diving Injuries Provider certifcation,and DAN encourages, when possible, regular practice to retain profciency. All skillsperormed in an emergency should be within the scope o ones training.

First Responder Roles and Responsibility

First aid is the provision o initial care or an injury or illness. Striving to (1) preserve

lie, (2) prevent the condition rom worsening and (3) promote recovery. The primarygoal o medical care is to perorm treatments or procedures without causing harm. Theadministration o supplemental oxygen is considered a very sae medical intervention.Provided the scene is sae and equipment is unctioning properly, the trained rescuercan eel confdent that oxygen provides benefts that may minimize injury and enhancerecovery.

Course Prerequisites

A current certifcation in ull cardiopulmonary resuscitation (CPR) is a prerequisite orthis program. Certifcation is accepted rom any recognized organization. There is nominimum age requirement to participate in this course. Some countries, states and localmunicipalities may have minimum age stipulations or the use o emergency oxygen.

Scuba Certifcation

Scuba diving certifcation is not a course prerequisite. This course teaches scuba diversand interested nondivers how to provide emergency oxygen frst aid to injured divers.Familiarity with diving equipment and diving terminology will make understanding thematerial easier. However, interested and inormed nondivers should be able to master thematerial.

Continuing EducationContinuing education is encouraged in the orm o additional training courses,supervised practice sessions, reading current literature and reresher training. Your DANInstructor can provide inormation about these programs. I you have urther questions,contact the DAN Education department.

How to use this handbook

Each chapter in this student handbook contains 3 distinct eatures.

Thebeginningofeachchapterhasalistoflearningobjectives.Thisistheinformation

you should be watching or as you read the material, watch the video and participate inclass discussions.

GreenboxeswiththewordNOTE:provideexplanationsthatareimportantto

understanding the material just presented.

TheyellowboxesunderAdvanceConceptscontainadditionalinformationbeyond

what is required or this course. It is enrichment or those students who want to knowmore.

1

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DAN Emergency Oxygen or Scuba Diving Injuries4

Overview of

Atmospheric

Gases2

Oxygen (O2)

Oxygen is a colorless, odorless, tasteless gas that comprises approximately 21 percento the Earths atmosphere. It is a vital element or survival and is needed or cellularmetabolism. Essential or lie, we may experience discomort, unconsciousness or deathwithin minutes when oxygen supplies are inadequate (hypoxia) or absent (anoxia).

Inhaled oxygen is primarily transported rom the alveolar capillaries throughout the

body by red blood cells (erythrocytes). Hemoglobin is the oxygen-carrying moleculewithin erythrocytes responsible or binding both oxygen and carbon dioxide. At rest,humans consume approximately 5 percent o the 21 percent oxygen in the air. Exhaledair thereore contains about 16 percent oxygen. These percentages will vary somewhat byindividual and level o activity, but they provide a tangible example o oxygen utilization.This eect has practical importance or rescue breathing as our exhaled breath containsless oxygen than normal air.

*NOTE: Although exhaled air has lower oxygen content than atmospheric air,

this amount is still sucient or eective rescue breaths.

Chapter 2 Objectives

1. What is oxygen (O2)?

2. How much oxygen is in both inhaled and exhaled airas we breathe?

3. How is oxygen transported to body tissues?

4. What is carbon dioxide, and how is it eliminated romthe body?

5. What is nitrogen gas?

6. What is carbon monoxide, and why is it dangerous?

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5DAN Emergency Oxygen or Scuba Diving Injuries

2

Advanced Concepts

During aerobic metabolism, our cells require oxygen to convert biochemicalenergy in the orm o nutrients (sugar, proteins and atty acids) into theenergy-storage molecule called adenosine triphosphate (ATP). The productiono ATP generates water, heat energy and carbon dioxide.

In health-care settings, blood oxygen levels are commonly measured with a pulseoximeter. This device, which is oten placed over the end o a nger, measureshemoglobin saturation the percent o hemoglobin binding sites occupied byoxygen through a color shit between oxygenated and deoxygenated bloodstates. Normal values while breathing air are 95-100 percent at low to moderatealtitudes. Values below this warrant medical attention. Hypoxemia (low levels oblood oxygenation) may necessitate prolonged supplemental oxygen therapy tomaintain values within normal levels.

The role o oxygen or diving injuries is to promote inert gas washout andenhance oxygen delivery to compromised tissues. When providing supplementaloxygen to an injured diver, a pulse oximeter is not used as a measure o oxygentreatment eectiveness or as an assessment o inert gas washout.

Carbon Dioxide (CO2)

Normal air contains very little CO2, only about

0.033 percent. CO2 is a waste product o cellularmetabolism. Exhaled gas rom respiration containsapproximately 4-5 percent CO2. Elevated levelso CO2 in a breathing gas mixture can lead todrowsiness, dizziness and unconsciousness thisis especially true when diving or breathing underincreased atmospheric pressure.

*NOTE: Although exhaled air contains higher levels o CO2 than air, rescue

breaths i perormed correctly should not result in signicant elevations inthe victims CO2 levels. In all cases where rescue breaths or other respiratorydevices are used (bag valve mask or positive pressure device), supplemental oxygenis recommended.

Advanced Concepts

CO2 is heavily concentratedin blood as bicarbonate(HCO3-) and serves a criticalrole in acid-base buering.The remaining CO2 is oundeither dissolved in plasma orbound to hemoglobin.

www.dan.org/training/eo2_atmosphere
http://www.dan.org/training/eo2_atmosphere

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6 DAN Emergency Oxygen or Scuba Diving Injuries

2

Nitrogen (N2)

Nitrogen exists in dierent chemical orms. As agas, N2 comprises about 78 percent o the Earthsatmosphere and in this orm is physiologically inert meaning it is not involved in cellular metabolism.In nondivers who remain at a constant ambient

pressure, the concentration o N2 in the exhaled airis also about 78 percent. In the case o divers whohave been breathing inert gas under pressure, thepercentage o exhaled nitrogen would be expected torise above this level while ogassing. However, sincenitrogen is an inert gas, it does not interere withresuscitation eorts during rescue breathing.

Inert gas absorption (nitrogen and helium) is associated with decompression sickness(DCS). Further discussion o DCS, and the role o oxygen, occurs later in this course.

Carbon Monoxide (CO)

Certain gases such as carbon monoxide (CO) interere with tissue oxygen delivery.CO binds more ercely to hemoglobin and inhibits both the uptake o oxygen and thedelivery to tissues. CO poisoning can lead to atal tissue hypoxia. Even small amountso CO in the breathing gas o a diver can be hazardous. Inspired gas partial pressures

increase with depth, so even small ractions o CO within a tank can become toxic whenbreathed under pressure.

The body requires a constant supply o oxygen to maintain cellular metabolism. In theabsence o oxygen, the bodys cells will rapidly deteriorate and die. Some cells are moresensitive than others to hypoxia. Nervous tissue (orming the brain, spinal cord andnerves) is typically very sensitive and will sustain irreversible damage within minutes oinadequate oxygen delivery.

Advanced Concepts

An elevation in exhaledCO2 levels, relative toinhaled air, is an indicationo metabolic activity. In

some medical settings, CO2levels in exhaled air aremonitored (capnography)and indicate cellularrespiration and adequacy oairway management.

Ingested or organic nitrogen (taken in as a solid, liquid orsupplement) is compounded with hydrogen and other ionsto orm amines the oundation o amino acids, whichmake up proteins. These amine groups are broken downand absorbed by our digestive system but do not enter ourtissues or bloodstream as absorbed gas (N2). As a result,ingestion o amines does not pose a decompression risk oralter our propensity or DCS. The only orm o nitrogenthat plays a role in DCS is the inorganic gas molecule N2.

Advanced Concepts

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DAN Emergency Oxygen or Scuba Diving Injuries 7

2

1. Oxygen is a clear, odorless gas essential

to lie.

a. True b. False

2. The atmospheric air we inhale contains

____ % oxygen.

a. 12

b. 16

c. 21

d. 27

3. The air we exhale contains

____ % oxygen.

a. 12b. 16

c. 21

d. 27

4. Oxygen is carried throughout the body

by _____ ______ cells.

5. Carbon dioxide is

a. A waste product o metabolism

b. A toxic gas

c. Essential or lied. An inert gas

6. Nitrogen comprises ____%

o atmospheric air.

a. 21

b. 27

c. 67

d. 78

7. Carbon monoxide is

a. A waste product o metabolismb. A toxic gas

c. Essential or lie

d. An inert gas

Review answers are on Page 72.

Chapter 2 Review Questions

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3

Oxygen is essential or lie. Within minutes o experiencing severe oxygen deciency(hypoxia) or the absence o oxygen (anoxia), we may experience severe discomort (whenassociated with elevation in carbon dioxide (C02)), unconsciousness or death.

Under normal circumstances, breathing ensures an adequate oxygen supply to tissues.The respiratory system provides an eective interace between the bloodstream andthe atmosphere and acilitates gas exchange (most critical to normal lie is the intake ooxygen and removal o carbon dioxide).

Carbon dioxide (CO2) results rom cellular metabolism and is transported by blood to thelungs, where gas exchange across the alveolar-capillary membrane enables elimination inthe exhaled breath. Elevated levels o CO2 provide the primary ventilatory drive, not lowlevels o O2. The rapid elevation o dissolved CO2 during short periods o breath-holdingprovides quick insight into the power o its infuence.

Respiration

and

Circulation

Chapter 3 Objectives1. What is hypoxia?

2. Why is oxygen necessary or lie?

3. Where does gas exchange occur in the body?

4. What body structures comprise the respiratorysystem?

5. What body structures are included in thecardiovascular system?

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The Respiratory System

The respiratory system is comprised o theupper airways (mouth, nose and pharynx),the trachea (windpipe) and the lungs. Keysupporting structures include the chest wall(ribs and intercostal muscles) and diaphragm

(a muscle critical to respiration that separatesthe thorax rom the abdomen). Surrounding thelungs and lining the inside o the chest wall isa thin membrane called the pleura. Althoughthis is one continuous membrane, its coverageo both the lungs and chest wall orms a doublelayer. Between these two pleural membranes isa potential space that contains a thin layer ofuid that acts as a lubricant, allowing ecientmovement o the lungs during breathing.

Air is drawn into the mouth and nose andpasses into the pharynx. The pharynx dividesintotwodistinctpassages:thetracheaandthe esophagus. The opening to the trachea isprotected rom ood (solids and liquids) duringswallowing by a fexible fap o tissue called theepiglottis. The esophagus, located behind thetrachea, is a conduit or ood and fuids en routeto the stomach.

In contrast to solids and fuids, air travels romthe pharynx through the larynx (voice box) and into the trachea. The trachea consists oa series o semicircular cartilaginous rings that prevent collapse. The trachea passes downinto the chest cavity and branches into the right and let bronchi, which enter the rightand let lungs, respectively. The bronchi progressively divide into smaller and smallertubes and nally into the alveoli. This branching pattern is commonly reerred to as thebronchial tree.

3

Advanced Concepts

The double-layered pleuralmembrane is made up o theparietal layer, which lines the

thoracic cavity, and the viscerallayer, which coats the organs.These two layers normallyremain closely adherent due toa slightly negative pressure thatkeeps them rom separating.Because there isnt a separationbetween these membranes, thisarea is known as a potential

space and only becomes atrue space i the membranesare injured or rupture. Apneumothorax orms rom theentry o air between these layers(intrapleural space) and mayorm rom escaped alveolarair subsequent to pulmonarybarotrauma.

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The alveoli, located at the end o the smallest branches o the respiratory tree, haveextremely thin walls and are surrounded by the pulmonary capillaries. The alveoli havebeen likened to tiny balloons or clusters o grapes.

In both lungs, millions o alveoli cover a combined surace area o around 750 square eet(70 square meters) or roughly the size o a tennis court.

3

02 in

C02out

LUNGS

capillaries

alveoli

oxygen incarbon

dioxide

out

capillary

red

blood cells

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A detergent-like substance, known as lung or pulmonary suractant, coats the innersurace o the alveoli. Pulmonary suractant decreases the surace tension o water within

the alveoli and thus reduces its tendency to collapse atthe end o expiration. I the suractant is removed, as mayoccur in a submersion incident, the alveoli may collapseand remain collapsed ater the inhaled water is removed

(or reabsorbed), severely compromising gas exchange.Large areas o collapsed alveoli are known as atelectasisand may evolve into a pneumonic ocus (pneumonia) ithey become inected.

The average adult alveolus has an estimated diameter o 200-300 micrometersand is only a cell layer thick. Alveoli lie adjacent to capillaries that are alsoone cell layer thick, and this proximity enables the rapid exchange o CO2 andO2. The thin alveolar-capillary membrane separates the content o the lungrom the bloodstream. I this membrane tears or becomes compromised due

to trauma rom a lung overexpansion injury (pulmonary barotrauma), it mayenablegastopassoutofthealveoliandintothebloodstream.Gasenteringthevascular system can travel throughout the body as an air embolism. This topic isdiscussed in more detail later in this course.

3Alveolar uid liningwith pulmonary surfactant

Type I alveolar cell

Interstitial uid

Pulmonarycapiliary

Alveolus

Alveolarmacrophage

Erythrocyte

Type II alveolar cell

Alveolus

Pulmonary

capiliaryO2

CO2

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Advanced Concepts

Two types o cells line the respiratory system. Onehas small hairlike structures called cilia; the othercells produce a mucous substance that is swept bycilia. These two cells work in concert.

The sticky mucous substance capturesoreign particles, and the ciliamove this mucus up intothe pharynx, where it can beswallowed and digestedtogether with any trappedoreign particles. In the caseo smokers, the mucus isthicker and the cilia are

damaged, which hindersthe lungs natural sel-cleaning mechanism.

The Cardiovascular System

The cardiovascular system includes theheart and blood vessels. It is a closed-circuitsystem with a primary purpose o pumpingblood, transporting oxygen and nutrients totissues and removing waste products.

The Heart

The heart is a hollow muscularorgan situated in the thoracic cavitybetween the lungs in a space calledthe mediastinum. A thinconnective tissue sac calledthe pericardium surrounds it.The pericardium like the

pleural linings o the lungs reduces riction betweenthe heart and surroundingstructures.

The heart is a strong muscularpump that, in the averageadult, has the capacity tobeat spontaneously at a rate oabout 70 times per minute (the

normal resting heart rate is

3

Pharynx

Trachea

Nose

Bronchialtubes

Alveoli

MucusCilia

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60-100 beats per minute and may be as low as 40 beats per minute in athletes7). Everyminute approximately 6 liters (about 1.5 gallons) o blood is pumped throughout thebody. When exercising, this output may double or triple depending upon the amount oexertion.

The heart is divided into a right and let pumpsystem (also known as the right heart or

pulmonary circuit and the let heart or systemiccircuit). The right heart receives deoxygenatedblood rom the venous system and pumps itto the pulmonary circuit to exchange gases.Oxygenated blood is returned to the let heart,where it is pumped to the systemic circuit.Transportation o blood through both circuitscompletes a circulatory cycle.

Blood Vessels

Blood leaves the let ventricle via the aorta,which then branches into smaller arteries tosupply the head, arms, torso and legs.

The blood vessels make up the vascular tree, with each branch leading to progressivelysmaller branches, which give rise to capillaries, the smallest o all blood vessels. Throughthese thin capillary walls, gases and nutrients are exchanged. Functionally, the heartand large blood vessels represent a pump-and-distribution system or the capillaries,responsible or supplying tissues with oxygen and nutrients and removing CO2 and other

metabolic waste products.From the peripheralcapillaries, theblood is gatheredinto small, thin-walled veins andreturned via largerveins to the atriao the heart. Most

veins direct bloodfow by means oone-way valvesthat prevent bloodrom traveling inthe wrong directionor pooling due togravity.

3

Capillary

Artery

Body Tissue

Blood flow Vein

O2

CO2

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Fetal Circulation

Within the uterus, the etus lives in a fuid-lled environment. As such, thelungs are not used or gas exchange, and circulating blood is largely shuntedaway rom pulmonary tissue. In the etus, gas exchange takes place in the

placenta, drawing available oxygen rom the mothers blood.

Descendingaorta

BLOOD OXYGEN

LEVEL

HIGH

MEDIUM

LOW

Left hepaticvein

Ductus venosus

Internaliliac artery

Lowerextremities

Gut

Kidney

Umbilicus

Umbilical vein

Umbilicalarteries

Placenta

Ductusarteiosus

Superiorvena cava

Inferior vena cava

Foramenovale

Righthepatic vein

Portal sinus

Portal vein

Rightatrium

Leftatrium

Pulmonarytrunk

3

Advanced Concepts

(continued on next page)

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15

Advanced Concepts

3

There are two unique passages in the etal circulation that allow blood tobypass the lungs. These two portals, known as the ductus arteriosus andoramen ovale, usually close soon ater birth with the babys rst breaths.

The ductus arteriosus (a duct between two arteries) enables blood comingrom the right ventricle to directly enter the aorta and thus bypass the lungs.Once this passage closes, blood is transported to the lungs, which are nowneeded or blood oxygenation. A vestige (remnant) o the ductus will remainas a ligament bonding the aorta and the pulmonary artery (ligamentumarteriosum or arterial ligament).

The oramen ovale (an oval-shaped hole) is a passage between the atria thatallows blood to shunt rom the right atrium to the let, thus bypassing thenonunctional lungs. At birth, when the pressures in the let atrium increase,this passage usually closes, too, leaving only a depression in the wall known

as the ossa ovalis. Closure o the oramen is incomplete in approximately25-30 percent o the population, thus leaving a patent (open) oramen ovale(PFO). The PFO is not physiologically relevant in many persons, but it maypredispose a small number o people to certain medical issues.

BloodBlood is a specialized fuid (actually a distinct organ system) that links therespiratory system to the rest o the body. Approximately 55 percent o ourcirculating blood volume is comprised o plasma, the visible fuid raction oblood. While mostly water, plasma also contains proteins, glucose, minerals,nutrients, waste products and dissolved gases. The cellular constituents oblood include erythrocytes (red blood cells; RBC), which transport oxygen andcarbon dioxide, and leukocytes (white blood cells; WBC), which play a criticalrole in inection control and infammatory responses. The third constituent is

platelets, cell ragments responsible or initiating the clotting process.

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1. Hypoxia is a condition o low

oxygen supply.

a. True b. False

2. An absence o oxygen

a. May cause cell death

b. Is known as anoxia

c. May cause unconsciousness

d. All o the above

3. Gas exchange takes place at the

a. Vein-artery interace

b. Long bone joints

c. Alveolar-capillary membrane

d. Muscle-nerve junctions

4. The respiratory system includes:

(Mark all that apply.)

a. Nose

b. Mouth

c. Trachea

d. Lungs

5. The circulatory system includes:

(Mark all that apply.)a. Mouth

b. Veins

c. Arteries

d. Heart



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4

The term decompression illness (DCI) describes signs and symptoms arising either

during or subsequent to decompression, and it encompasses two dierent but potentiallylinkedprocesses:

Decompressionsickness(DCS) Arterialgasembolism(AGE)

While the underlying cause o these two conditions may be dierent, their initial medicalmanagement (rst aid) is the same.

The most important initial actions perormed in diving accidents

are early recognition and the use o supplemental oxygen.

Decompression

Illness

(DCI)

Chapter 4 Objectives1. What are the most important initial actions in responding

to diving accidents?

2. What is decompression illness (DCI)?

3. What is the primary cause o decompression sickness(DCS)?

4. What are the primary symptoms o DCS?

5. What is arterial gas embolism (AGE)?

6. What is the primary risk actor or AGE?7. Why is it important to seek medical evaluation when DCI

is suspected?

8. What are the most prevalent symptoms o DCI?

9. What are the typical onset times o DCS and AGEsymptoms?

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Decompression Sickness

DCS results rom bubbles ormed within tissues or blood rom dissolved inert gas (N2 orhelium). The size, quantity and location o these bubbles determine the location, severityand impact on normal physiologic unction. Besides the anticipated mechanical eectsthat can cause tissue distortion and blood-fow interruption, bubble ormation maytrigger a chain o biochemical eects. These include activation o clotting mechanisms,

systemic infammation, leakage o fuids out o the circulatory system and reactivevasoconstriction. These eects may persist long ater bubbles are gone and may play asignicant role in the duration and severity o clinical signs and symptoms.

While the eects o bubbles impact us on a systemic level, specic signs and symptomsare thought to result rom either bubble accumulation or its impact on specic areas.Examples include joint pain, motor or sensory dysunctions and skin rash.

DCS is rarely lie-threatening. Early treatment with high concentrations o O2 (as closeto 100 percent as possible) has been shown to speed symptom resolution and optimizethe impact o recompression therapy.8 Though symptom resolution is a desired eect ooxygen rst aid, it is important to emphasize that it should not be considered a denitivetreatment or arbitrarily stopped when symptoms resolve.

Arterial Gas Embolism (AGE)

Arterial gas embolism in divers typically results rom a lung-overexpansion injury. Thegreatest risk or this injury occurs in shallow water and may result rom breath-holdingin as little as 4 eet (1.2 meters) o sea water. Lung-tissue trauma can allow the entranceo breathing gas into the blood vessels returning to the heart (pulmonary veins). Thesebubbles, i transported to the brain, can cause rapid and dramatic eects.

TheprimaryriskfactorforAGEisbreath-holdingduringascent.Otherpotentialriskactors include underlying conditions like lung inections and preexisting diseases likeasthma that may increase the risk o air trapping.

ItisimportanttostatethatnotallpulmonarytissueinjuriesresultinAGE(thisincludes lung-overexpansion injuries in divers). Pulmonary trauma rom stab wounds,projectiles or blunt orce can also lead to lung-tissue damage and enable the escapeo intrapulmonary (within the lungs) air without causing arterial bubbles. Signso pulmonary barotrauma include extra-alveolar air (air outside the lungs) such aspneumothorax, subcutaneous emphysema (air beneath the skin), mediastinal emphysema(air in the mediastinum) and pneumopericardium (air trapped around the heart).Depending on the location o gas collection, signs and symptoms may include chest pain,changes in voice pitch, diculty breathing or swallowing, gas bubbles elt under the skin(typically around upper thorax, neck and/or ace) and cyanosis (bluish coloration o thelips).

4

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4

Normal alveoli

Expansion ofalveoli

Subcutaneous emphysema

Cerebral air embolism

Pnumomediastinum

Rupture ofalveoli

Pneumothorax

Air enterspulmonary capillary

Pulmonary barotrauma with subsequent arterial gas embolism and representation o brain

(cerebral)injury.RecreatedbytheDiversAlertNetworkfromLancet2011;377:154

www.dan.org/training/eo2_age
http://www.dan.org/training/eo2_age/

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4

Advanced Concepts

AseparatebutrelatedconcernisAGEthatoccurssecondarytovenousbubbles bypassing the pulmonary lter and entering the arterial systemdirectly. The process through which blood passes rom the right side o thecirculatorysystemtotheleftandbypassesthepulmonarylteriscalled

shunting in this case, right-to-let shunting. Shunting may occur througha physiologically relevant PFO or passage through the lungs (transpulmonaryshunt). Regardless o the method, problems can occur when bubbles enter thearterial circulation. Bubbles may impact the central nervous system (CNS) andcause acute neurological symptoms. Symptom onset in this scenario coulddevelop ater a longer interval than the 10-15 minutes typically describedincasesofAGEsincethesourceofthearterializedbubblesisfromthevenous system and not pulmonary barotrauma. It is important to note thatwhile bubbles in the systemic system are undesirable, their presence does

not automatically cause symptoms. Bubbles have been visualized in the letheart ollowing decompression in subjects who have not gone on to developsymptomatic DCI.

Oxygen and the Importance of Proper Medical Evaluation of DCI

The diagnosis o DCI is based on history and clinical ndings there is no diagnostictest. Symptoms can range rom very mild to severe and, particularly in the ormer case,may be dismissed by divers or appear to resolve by the time medical care is sought.

In some cases the use o oxygen leads to symptom resolution, which may prompt thedecision to orego medical assessment. DAN recommends seeking prompt medicalevaluation in all cases o suspected DCI regardless o the response to oxygen rst aid. Forthose tempted to avoid medical assessment, be advised that symptoms may recur, and therisk o recurrence may be reduced with hyperbaric treatment.

Common Signs and Symptoms of DCI

While providing emergency oxygen to an injured diver, you may see their conditionchange with time. In the case o complete symptom resolution, continue oxygenadministration, and seek medical attention regardless o perceived improvement.

Injured divers may have one or more o the ollowing signs and symptoms. The list isranked in order o presentation requency based on Project Dive Exploration (PDE) datarom 2,346 recreational dive accidents reported to DAN rom 1998 to 2004.

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0

0.04

0.042.8

0.31.8

0.32.1

0.41.8

0.8

1.2

7.9

7.9

1.36.5

3.4

3.89.5

18.7

6.119.4

40.8

27.4

40.6

63.4

68.0

13.6

0.95.6

0.4

Pain

Cardiovascular

Bladder, bowel

Lymphatic

Auditory

Consciousness

Coordination

Pulmonary

Mental status

Muscular discomfort

Cutaneous

Motor weakness

Dizziness/Vertigo

Constitutional

Numbness, paresthesias

20 40 60

Occurence (% of patients)

All symptoms

First symptom

80 100

Classication and requency distribution o initial and eventual maniestations o decompression illness in2,346 recreational diving accidents reported to Divers Alert Network rom 1998 to 2004.

Pain (Initial symptom in 41 percent o cases)

Commonly associated with neurological symptoms, it has been characterized asa dull, sharp, boring or aching sensation in or around a joint or muscle. It maybegin gradually and build in intensity or be so mild that it is disregarded.

Movement o the eected joint or limb may or may not make a dierence in theseverity o the pain. The pain may be out o proportion to the amount o work or

exerciseperformedandmaybereferredtoasunusualorjustdifferent.

DCI pain can be dicult to distinguish rom normal aches and pains. Symptoms

can mimic other illness such as viral inections, muscle or joint pain, atigue romexertion and other nonspecic discomorts.

Neurological: Numbness/Paresthesia (Initial symptoms in 27 percent o cases)

Paresthesia/anesthesia/dysesthesiaaretermsthatrefertoalteredsensations and may present as abnormal eelings (paresthesia),decreased or lost sensation (anesthesia) or hypersensitivity (dysesthesia).Paresthesia is commonly characterized as a pins-and-needles sensation.These altered sensations may only aect a small patch (or patches) o

4

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4

skin and may go unnoticed by the diver until they are revealed by athorough medical evaluation. A diver may complain that an extremity

hasfallenasleeporafunnybonehasbeenhit.Numbnessandtinglingmost oten occur in the limbs and may be associated with complaintssuch as a cold, heavy or swollen sensation.

Constitutional Symptoms (Initial symptoms in 14 percent o cases)

Thesearegeneralizedsymptomsthatdonotimpactaparticularparto the body. Examples include extreme atigue, general malaise andnausea.

Extremefatigue:Itisnotunusualtobefatiguedafterascubadiveorother physical activity. The atigue associated with DCI is typically moresevere and out o proportion with the level o exertion required by thedive. The diver may want to lie down, sleep or ignore personalresponsibilities such as stowing gear or cleaning equipment.

Balance and Equilibrium (Initial symptoms in 6 percent o cases) Vertigo(spinningsensation):Vertigopresentingduringorafterthe

dive should be considered a serious symptom suspicious o innerear/vestibular involvement.

o There are several non-DCI-related causes or such symptoms,and these include round- or oval-window rupture, alternobaricvertigo and caloric vertigo.

Dizziness:Afeelingofunsteadiness,whichmayalsobecharacterizedas light-headedness, is commonly associated with nausea.

Muscular Weakness (Initial symptom in 4 percent o cases)

This symptom may present as diculty walking due to decreasedmuscular strength or limb paralysis.

Cutaneous (Skin) Symptoms (Initial symptom in 3 percent o cases)

Skin signs are oten located on the chest, abdomen, back, buttocks orthighs. Rashes commonly migrate (move to dierent parts o the body).Eected areas may be tender or itch and are thus oten conused withallergies or contact dermatitis.

Altered Mental Status (Initial symptom in 1.2 percent o cases)

Symptoms may include conusion, personality changes or speechdisturbances (slurring o words or nonsensical speech).

Bowel and Bladder (Initial symptom in 0.04 percent o cases)

Spinal cord DCS may injure the nerves responsible or bladder andbowel control. Sometimes people will require urinary catheterization.

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*Any suspicion o neurological symptoms should prompt immediateoxygen therapy and transportation to a medical acility.

Other Signs and Symptoms of DCI

Alteredlevelofconsciousness:Identiedasinitialsymptomin

0.4 percent o cases.

Audiovestibularorinner-earDCS:Thisrelativelyraremanifestationis associated with deep heliox diving.

LymphaticDCS:Identiedasaninitialsymptomin0.3percentofcases.This symptom is oten characterized as localized swelling aecting thetrunk and shoulders.

Visualdisturbance:Lossorblurringofvisionorlossofvisualelds

Difcultybreathing:Thismaybetheresultofpulmonarybarotraumaor a severe orm o DCS known as the chokes (a rare but lie-threateningcondition caused by an overload o venous gas emboli that severelyimpacts cardiorespiratory unction). There are also many other causeso respiratory compromise not necessarily related to or associated withDCI all o which should prompt medical evaluation.

Convulsionsarerare.

Epidemiology of Decompression Illness

DCI is an uncommon event, which nonetheless warrants attention and concertedeorts to prevent. Based on 441 conrmed or possible incidents o DCI reerencedin the 2008 DAN Annual Diving Report, 3.9 percent were classied as possibleAGE.1

The occurrence o DCS varies by population. Based on DAN data, the per-dive rateamong recreational divers is 0.01-0.019 percent; among scientic divers its 0.015percent; or U.S. Navy divers its 0.030 percent; and or commercial divers its 0.095percent.1,2

Previously published per-dive DCS rates based on 135,000 dives by 9,000recreational divers were 0.03 percent. This rate was higher in those who perormeddeep cold-water wreck dives versus the group aboard warm-water liveaboards. TheincidenceofDCSfromwarm-waterliveaboardswas:2/10,000(0.0002)andamongcold-water wreck divers in the North Sea 28/10,000 (0.0028).3

4

http://www.DAN.org/

medical/report/index.asp
http://www.dan.org/medical/report/index.asp/

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DCI Symptom Onset

While the timing o symptom onset varies, the majority o people complain o DCSsymptoms within six hours ollowing a dive. Symptom onset may be delayed by asmuch as 24 hours, though beyond this time rame the diagnosis becomes increasinglyquestionable.

IncontrasttoDCS,AGEwilltypicallyshowamoredramaticarrayofneurological

symptoms, most o which will show up immediately upon suracing or within 15 minutesrom the time o injury. As one might expect, sudden neurological injury that leads tounconsciousness may result in drowning.

Recompression Therapy

An injured diver may eel better or experience reduced symptom severity ater receivingemergency oxygen. Despite symptom improvement, and in some cases resolution, diversshould still seek medical evaluation. The primary medical concern is that symptoms(especially neurological symptoms) may recur when supplemental oxygen therapy isstopped. This is one o the reasons DAN recommends transportation to the nearestmedical acility or evaluation. DAN is always available to provide inormation toemergency medical sta regarding diving injuries and the potential benet o hyperbarictreatment. DAN also provides evacuation assistance and care coordination with treatingacilities.

Prolonged treatment delays, usually measured in days, may reduce the eectiveness otreatment and may extend the time needed to achieve optimal symptom resolution. Itshould be understood, however, that in the majority o less severe cases, minor delays oa ew hours rarely impact the nal treatment outcome.

Residual SymptomsResidual symptoms ollowing hyperbaric oxygen treatment are not uncommon, especiallyin severe cases or when considerable delays (sometimes measured in days) in treatmentinitiation have occurred.

Divers who experience persistent symptoms ollowing hyperbaric oxygen therapy shouldremain under the care o a hyperbaric physician until symptoms have resolved or urthertherapy is deemed either unnecessary or unlikely to provide urther benet. A decision toreturn to diving should be made in consultation with a physician knowledgeable in divemedicine.

4

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4

1. Decompression illness (DCI) includes:

a. Decompression sickness (DCS)

b. Arterial gas embolism (AGE)

c. Both o the above

2. The most important initial actions

in responding to diving accidents are

to recognize there is a problem and

administer 100 percent oxygen.

a. True b. False

3. DCS is caused by:

a. Breath-hold during descent

b. Breath-hold during ascentc. Inert gas bubbles in the body

4. The primary risk actor or AGE is

a. Breath-hold during descent

b. Breath-hold during ascent

c. Inert gas bubbles in the body

5. Describe why it is important to seek

medical evaluation when DCI is

suspected.

___________________________________

___________________________________

___________________________________

___________________________________

6. List the ve most requent symptoms

o DCI.

_______________________________

_______________________________

______________________________________________________________

_______________________________

7. Initial DCS symptoms

a. Occur within 15 minutes o the time

o injury

b. Typically occur within six hours

o suracing

c. May be delayed up to 24 hours

d. Both b and c

8. AGE symptoms

a. Occur within 15 minutes o the time

o injury

b. Typically occur within six hours

o suracing

c. May be delayed up to 24 hoursd. Both b and c

9. Returning to diving ollowing

decompression illness should be done in

conjunction with a physician

knowledgeable in dive medicine.

a. True b. False



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Oxygen

and

Diving

Injuries5

The most common diving injuries or which oxygen use is recommended are arterial gasembolism(AGE)anddecompressionsickness(DCS).InthecaseofAGE,bubblesmayenter the arterial system secondary to lung overexpansion and lung-tissue rupture. In thecase o DCS, problems arise when gas dissolved in body tissues during a dive comes outo solution in the orm o bubbles during or ollowing decompression. Bubbles may causetissue disruption, compromise blood fow and/or trigger infammatory responses, whichmay result in symptoms.

Chapter 5 Objectives1. What are the benets o providing a high concentrationo oxygen to an injured diver?

2. How does establishing a gas gradient help theinjured diver?

3. What is the primary goal o emergency oxygen orinjured divers?

4. What critical actors impact the percentage o oxygendelivery when using a demand valve?

5. What is the initial fow rate or constant-fow oxygendelivery systems?

6. What is the priority or oxygen delivery in remote areas?

7. What are the concerns or oxygen toxicity when

delivering emergency oxygen rst aid?

8. What are the symptoms o nonatal drowning?

9. What is the rst responders role in a nonatal drowning?

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5

Though most cases o DCS are mild and do not pose an immediate risk to lie, impairedcirculation or unction o vital areas like the brain and spinal cord can result in severeneurological symptoms. These can range rom mild tingling and pain to weakness,paralysis, diculty breathing, unconsciousness and even death.

IncontrasttoDCS,AGEiscommonlyassociatedwithlung-overexpansioninjuryandcanresult in acute neurological symptoms including unconsciousness. Bubbles entering the

arterial system through damaged lung tissue can quickly travel to the brain and interruptcirculation. The goal o rst responders is to enhance blood oxygen levels and speedbubble size reduction by establishing a gas gradient.

Oxygen administration in the setting o a suspected diving injury creates a partialpressure gradient that helps in two key ways. The rst is an acceleration o inert gas(nitrogen and/or helium) elimination. This process may reduce bubble size and improvecirculation. The gradient also enhances oxygen delivery to injured or ischemic tissues(areas with poor circulation), which can reduce pain and limit or reverse hypoxic injury.Oxygen administration may also reduce edema (swelling), which can urther improve theeciency o tissue oxygen delivery.

The DAN Oxygen Provider course emphasizes the use o oxygen or diving injuries andnonatal drowning but does not address other indications or oxygen treatment.

Oxygen Flow Rates

The primary goal o emergency oxygen or injured divers is to deliver the highestpercentage o inspired oxygen possible. Keeping this goal in mind is key to deliveringoptimal care.

Therearetwovariablesthatimpactdeliveredoxygenconcentrations:masktandowrate (measured in liters per minute or lpm). In the case o demand valves, proper t andseal are critical as fow rate is not adjusted. When using constant-fow systems, mask tis still crucial as leaks result in decreased inspired ractions o oxygen (FiO2). Enhancedfow rates are an inecient way to compensate or a poor tting mask.

Delivery Device Flow Rate Inspired Fraction+

Nasal cannulae 2-4 lpm 0.3 (30%)*

Oronasal mask (no reservoir bag) 10 lpm 0.50.6 (50%60%)*

Nonrebreather mask 10-15 lpm 0.8 (80%)**

Bag valve mask 15 lpm 0.90.95 (90%95%)

Demand valve N/A 0.90.95 (90%95%)

*May vary with respiratory rate

**Less variation with changes in respiratory rate

+ Delivery ractions vary with the equipment and techniques used. This table summarizes various oxygen-delivery systems andpotential values o inspired oxygen with their use.

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Nasal cannulae are generally operated at relatively low fow rates o 2-4 lpm. Nasalcannulae are the least ecient method o oxygen delivery, typically delivering ractions nogreater than 0.3 (30 percent). Simple ace masks may deliver ractions o 0.5-0.6 at fowrates between 10-15 lpm.

Nonrebreather masks can deliver a higher raction but probably still no greater than 0.8.Demand valves are appropriate or conscious and spontaneously breathing divers and

with careul mask management may deliver ractions up to 0.9-0.95.

Accidents requently occur in remote locations or ar away rom medical services, andoxygen supplies are generally limited. Rescuers ace the dilemma between maximizinginspired ractions and limiting fow rates in an attempt to conserve oxygen supplies. Thepriority should always be to maintain the highest inspired ractions possible.

As shown in the above table, the best solution is the demand valve (or manually triggeredventilator being used as a demand valve). I continuous-fow delivery is required or theonly method available, start at 10-15 lpm and increase or decrease in increments based

on the needs o the diver, ensuring that the reservoir bag remains ull.

Flow rates above 10 lpm will not cause harm but will deplete oxygen supplies aster. Ithe next level o care is accessible beore the supply is exhausted, higher fow rates can beused to maintain optimal oxygen ractions and enhance patient comort. Any perceived orsuspected worsening in a divers condition should prompt reassessment.

Hazards of Breathing Oxygen

Oxygen toxicity can occur when one breathes highconcentrations o oxygen or prolonged periods

or while under pressure. Oxygen toxicity occursintwoforms:centralnervoussystem(CNS)andpulmonary (lung) toxicity. In CNS oxygen toxicity,seizures may develop when someone breathesoxygen at greater than 1 atmosphere absolute(ATA) pressure. The risk o acute toxicity increaseswith elevations in partial pressure. For this reason,the accepted sae recreational limit or oxygenpartial pressures while underwater is 1.4 ATA.

Breathing high concentrations o oxygen orprolonged periods at the surace can causepulmonary oxygen toxicity, which is quitedistinct rom CNS toxicity. In this setting, lungtissue may become irritated when breathing elevated oxygen concentrations. Theunderlying mechanism or this is the production o oxygen ree radicals in a quantity thatoverwhelms our cellular antioxidant deenses. Initial symptoms may include substernal(behind the sternum) irritation, burning sensation on inspiration and coughing. The mostsevere symptoms may occur ater about 12 to 16 hours o exposure at 1 ATA.4 The time

5

Advanced Concepts

Chemical oxygen systems

deliver neither sucient fowrates nor sucient oxygenvolume to be eective.The average measured fowrates were 3 lpm (Pollockand Hobbs, 2002) and lessthan 2 lpm (Pollock andNatoli, 2010) with total

fow durations o littlemore than 15 minutes orone reactant set.

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5

to initial symptom onset is expected to reduce at higher partial pressures (greater than 1ATA). Symptoms may be seen rom 8 to 14 hours at 1.5 ATA5 and rom 3 to 6 hours at 2ATA.4,5 At higher pressures, symptoms may occur more quickly but are oten less severedue to limited exposure times. The prevailing concern with PO2 levels greater than 2.5

ATA and 3 ATA is CNS toxicity.4,5,6

CNS toxicity is not a concern or the oxygen provider rendering rst aid. Pulmonary

oxygen toxicity is also not a signicant concern or rst responders delivering oxygen atmaximal concentrations at ground or sea level or less than 12-24 hours.

Nonfatal Drowning

Nonatal drowning reers to a situation in which someone almost died rom beingsubmerged underwater and was unable to breathe. In the case o prolonged asphyxia (notbreathing) or reduced cardiac and lung unction due to submersion, oxygen therapy maybe crucial. While nonatal-drowning victims may quickly revive, lung complications arecommon and require medical attention. In addition, fuid and electrolyte imbalances maydevelop with the potential or delayed symptom onset.8

Symptoms o nonatal drowning may include diculty breathing, bluish discoloration othe lips, abdominal distention, chest pain, conusion, coughing up pink rothy sputum,irritability and unconsciousness. Victims may also be anxious or cold and would benetrom removal o wet clothes and possible treatment or hypothermia.8

As a rst responder, your primary role is to monitor vital signs, provide supplementaloxygen and transport to the nearest medical acility as soon as possible.

NOTE: Keep yoursel sae. Avoid in-water rescue unless trained and properlyequipped.

www.dan.org/training/eo2_drowning
http://www.dan.org/training/eo2_drowning/

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5

1. Providing a high concentration o

oxygen to an injured diver may provide

these benets: (Mark all that apply.)

a. Acceleration o inert gas elimination

b. Reduce bubble size

c. Enhance oxygen delivery to tissues

d. Reduce swelling

2. The primary goal o the highest

concentration o oxygen possible to

an injured diver is to acilitate inert gas

washout and improve oxygen delivery to

compromised tissues.

a. True b. False

3. Percentage o oxygen delivered when

using a demand valve is infuenced by

a. Flow rate

b. Mask t

c. Mask seal

d. Both b and c

4. The initial fow rate or constant-fow

oxygen delivery is

a. 2-4 lpm

b. 10-15 lpm

c. 20-25 lpm

d. The rate the injured diver will tolerate.

5. In remote areas, the priority in oxygen

delivery is

a. To conserve oxygen supplies

b. To maximize highest inspired

raction o oxygen

c. Limit the fow o oxygen

6. Oxygen toxicity, whether CNS or

pulmonary, is not a concern or

oxygen rst aid to an injured diver.

a. True b. False

7. List eight symptoms o nonatal drowning.

_____________________________

_____________________________

_____________________________

_____________________________

_____________________________

_____________________________

_____________________________

_____________________________

8. As a rst responder to a nonatal

drowning, your primary role is to

a. Monitor vital signs

b. Provide supplemental oxygen

c. Transport to the nearest

medical acility

d. All o the above



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Handling

Oxygen

Safely6

Oxygen is not fammable, but all substances need oxygen to burn and may burn violentlyin an environment o pure oxygen. Problems associated with the use o properlymaintained emergency-oxygen devices are rare. Three elements heat, uel and oxygen are required or a re to exist. This is commonly called the re triangle. Emergency-oxygen systems will always have at least one element, and that is oxygen.

DAN Oxygen Providers should reduce

the risks o handling oxygen. Be sure that the hazards romboth the uel (oil deposits and hydrocarbons are commonlyused as lubricants or diving and are ound on dive boats)and heat rom the sun and rapid opening o the oxygencylinder valve are minimized.

Where Does Pure Oxygen Come From?

Fractional distillation o air yields pure oxygen.Air is rst ltered to remove any debris and dirt.Compressed to very high pressures, it is dried

to remove water vapor. To liquey the gas, it

OXYGEN H

EAT

FUEL

Chapter 6 Objectives

1. What is the re triangle, and how is oxygen involved?

2. What two steps should be implemented to reducethe risks o handling oxygen?

3. What are the saety precautions that should beimplemented when using oxygen equipment?

4. What grade o oxygen should be utilized ordiving rst aid?

5. What documentation is required to receive an

oxygen ll?

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is cooled to very low temperatures and allowed to slowly rewarm. As it is rewarming,various components o air (primarily oxygen and nitrogen) are captured and stored inseparate containers as they reach their particular boiling points.

There are many grades o oxygen, but the three primary ones that DAN Oxygen Providersneedtoconsiderare:

Aviator-gradeoxygenMedical-gradeoxygen

Industrial-gradeoxygen

Each grade must be 99.5 percent pure oxygen; however, dierences exist in how thecylinders are lled, aecting the overall purity o the oxygen. For example, to preventreezing at high altitudes aviator-grade oxygen has a lower moisture content thanmedical-grade oxygen.

The lling procedures or medical-grade oxygen require that an odor test is conducted

and the cylinder contents be evacuated beore the ll. When odors are detected ordamage to the valve or cylinder is observed, medical-grade oxygen cylinders are cleanedbeore returning them to use.

Industrial-grade oxygen is not recommended or use with dive injuries. Industrial-gradeoxygen guidelines allow or a certain percentage o impurities and other gases to becontained within the cylinder. While both aviator- and medical-grade oxygen are suitableor breathing, industrial-grade oxygen may not be. The procedures or lling industrialoxygen cylinders do not ensure that the oxygen is ree o contamination.

Safety Precautions When Using Oxygen

Oxygen cylinders require the same care as scuba cylinders with a ew additionalprecautions:

Donotallowtheuseofanyoilorgreaseonanycylinderordevicethatcomesincontact with oxygen. The result may be a re.

Oxygencylindersshouldnotbeexposedtotemperatureshigherthan125F(52C)instorage (or example, in a car trunk).

Donotallowsmokingoranopenamearoundoxygenandoxygenequipment.

Remembertoprovideadequateventilationwhenusingoxygen.Inaconned,poorlyventilated space (the cabin o a boat, or example), the oxygen concentration may buildup and create a re hazard.

Useonlyequipment(cylinders,regulators,valvesandgauges)madetobeusedwithoxygen. Avoid adapting scuba equipment or use with oxygen.

Visuallyinspecttheconditionofvalveseatsandoxygenwashers,andmakesurethematerials are compatible or oxygen use.

6

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Keepthevalvesclosedwiththesystempurgedwhentheunitisnotinuse.Closevalveson empty cylinders. Empty cylinders should be relled immediately ater use.

Anoxygencylindershouldalwaysbesecuredsothatitcannotfall.Whencarryinganoxygen cylinder by hand, carry it with both hands, and avoid holding it by the valve orregulator. When transporting an oxygen cylinder in a car, secure and block the cylinderso it does not roll.

Oxygen Cylinder Filling

In many areas, medical-grade oxygen is considered a prescriptiondrug, and that can make it dicult to rell your emergencyoxygen cylinder. The most common method odocumenting the need or oxygen is a prescription;however, prescriptions are or diagnosed medicalconditions. The prescription allows or use only by theindividual who was given the prescription.

The other method o obtaining an oxygen cylinder ll isby providing documentation o training in the use oemergency oxygen. Like your scuba diving certicationcard, your DAN Oxygen Provider card is yourdocumentation o appropriate training. Since retraining isrequired every two years, you will need to maintain yourskills by taking an oxygen reresher program. Ask yourDAN Instructor about retraining opportunities.

Some countries, states and local governments haveregulations that require that oxygen supply companiesdocument all medical-grade oxygen distillation, cylindertranslls and sales. These governmental agencies routinelyinspect the acilitys operations and documentation toveriy compliance with these regulations. Other areashave ew or no regulations regarding the distribution ooxygen.

I you have any questions regarding oxygen rells or i

you have diculty obtaining an oxygen cylinder ll,contact the International DAN oce in your regionor assistance.

6

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6

1. Oxygen is one element o the re triangle.

a. True b. False

2. The risks o handling oxygen can

be reduced by

a. Keeping the oxygen units ree

o hydrocarbons ound in oils and

lubricants oten ound on dive boats

b. Opening the oxygen cylinder slowly

c. Keeping the unit away rom the heat

o the sun

d. All o the above.

3. Saety precautions to implementwhen using oxygen cylinders include

(mark all that apply):

a. do not allow any oil or grease to come

in contact with oxygen cylinder

b. do not expose oxygen cylinders to

high temperatures or allow smoking/

open fames around oxygen

c. provide adequate ventilation when

using oxygen

d. only use equipment made or use with

oxygen.e. always secure the oxygen cylinder so

it cannot all or roll.

4. With what grade o oxygen should

an oxygen cylinder or diving rst aid

be lled?

a. Aviator grade

b. Medical grade

c. Industrial grade

d. Either a or b

5. Methods or obtaining oxygen lls

may include:

a. Prescription

b. Documentation o training in

oxygen delivery

c. Both a and b



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7

Oxygen Delivery Systems

The oxygen delivery system consists o an oxygen cylinder, a pressure-reducing regulator,

a hose and a ace mask. There are many oxygen equipment options. Note the ollowingspecic guidelines or the use o oxygen equipment or scuba diving injuries.

Oxygen cylinders. Enough oxygen should be available to allow or continuous delivery toan injured diver rom the time o injury at the arthest possible dive site to the next levelo emergency response. The duration o common portable oxygen cylinders varies basedon the size o the oxygen cylinder, the oxygen fow rate and the type o delivery device.However, it is common or a single portable oxygen cylinder to last rom 15 minutes to60 minutes. Nonportable oxygen cylinders can last up to eight hours or more.

Chapter 7 Objectives1. What are the components o an oxygen delivery

system?

2. What two actors infuence what cylinder is appropriate?

3. When should the oxygen provider switch to a ullcylinder?

4. Which oxygen regulator is preerred or diving rst aid?

5. Why is a demand valve the rst choice or delivering

oxygen to an injured diver?6. What are the advantages and disadvantages o the

ollowing?a) Manually triggered ventilator

b) Bag valve mask

OxygenDeliverySystems

andComponents

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Oxygen regulators. Oxygen delivery occurs viathree common types o regulators. One type is aconstant-fow style, which can deliver a xed oradjustable fow o oxygen. Another is the demandregulator; it unctions like a scuba regulatorand delivers oxygen when the demand valve is

activated. The third style is the multiunctionregulator, which combines the eatureso both the demand and constant-fowregulators.

A multiunction regulator is preerred overthe other styles because it will allow a rescuerto provide as close to 100 percent oxygen as possibleto two injured divers simultaneously and permits various mask options.

All DAN Oxygen Units come equipped with multiunction regulators.

Hoses and tubing. Certain types o constant-fow masksprovide oxygen-sae, clear plastic tubing to connect themask to the regulator. Since an oxygen demand valverequires approximately 50 psi (3.5 bar), an intermediatepressure hose attaches to the threaded outlets on both theregulator and valve.

Oxygen masks. An oxygen mask held tothe ace permits the inhalation o higherconcentrations o oxygen. Using a demandvalve with an oronasal mask can deliveroptimal oxygen concentrations whilealso preserving supplies or as long aspossible.

Common constant-fow masksprovide rom 35 to 75 percent

oxygen. For diving injuries, it isrecommended that oxygen bedelivered by a demand valve andoronasal mask to provide as closeto 100 percent inspired oxygen aspossible.

7

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Oxygen System Components

Common oxygen cylinders. Portable oxygen cylinders come in a varietyo sizes. As a DAN Oxygen Provider, you are primarily concernedwith capacity. Remember, you should have enough oxygenavailable to transport an injured diver to the nearest appropriatemedical acility.

I you conduct shore diving where there is an emergency medicalservice (EMS) in place, you may need only a 15-minute supply.

When you dive o a boat close to shore, you may need a one- ortwo-hour supply. I you dive ar oshore and assistance is hoursaway, you may want to consider carrying a nonportable oxygencylinder or multiple portable oxygen cylinders.

Consult your DAN Instructor about which cylinder size is mostappropriate or your use. The duration o a cylinders oxygencontent depends on the consumption o gas. An oxygen cylindershould be changed to a ull one when the pressure drops below200 psi (14 bar). However, i only one cylinder is available, itshould be used until the oxygen supply is depleted. When usinga constant-fow oxygen regulator, it is easy to estimate how long a cylinder will last.

To approximate how long an oxygen cylinder will last with a constant-fow regulator, usethiseasyformula:

Capacity in liters ow in liters per minute =

approximate delivery time

For example, i a cylinder holds 640liters and the oxygen fow rate is 15liters per minute, the cylinder willlast approximately 43 minutes. At 10liters per minute, the same cylinderwill last 64 minutes.

When a diver uses a demand

inhalator valve, it is more dicult todetermine an exact time o supply.The rate at which the oxygen isused will depend on the injureddivers breathing rate and volume.Generally,theaverageoxygenuseon a demand valve is equivalent to8 to 10 liters per minute. Demand-style is preerred because no oxygen

is wasted, and usually the oxygensupply lasts longer.

7

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Cylinders are made o either aluminum or steel and are subject to periodic visual andhydrostatic testing. Testing times are generally established by law or regulations, andrequirements vary. Common hydrostatic testing intervals range rom two to 10 years. Inthe United States, the hydrostatic testing requirement is ve years.

For easy identication and to minimize the risk o using cylinder contents or anunintended purpose, oxygen cylinders are color coded. Common oxygen cylinder color

combinations include green (United States), black with a white shoulder (Australia, NewZealand, United Kingdom and others) and white (Canada and Europe). Ask your DANInstructor or the color-coding requirements o your region. Oxygen cylinders also shouldbe clearly labeled.

Pressure regulators. The pressure regulatorreduces the cylinder pressure to a sae workingpressure compatible with a demand valve orconstant-fow equipment. All regulators mustattach to the oxygen cylinder. Various methodso attachment are available.

In some areas, pins engage matching holes onthe cylinder valve. This pin-indexed valveiscalledaCGA870medicaloxygenvalve.

These pins are aligned to prevent an oxygenregulator rom being used on a cylinder that maycontain another gas. This system is important inlocations where there are various gases in

use, and each requires its own regulatorand cylinder. Pin placement is specic oreach gas.

In other areas, oxygen cylinders may havethreadedgas-outletvalves(CGA540medical oxygen valve and bull-nose valvethat will accept regulators intended onlyor medical oxygen use.

Ask your DAN Instructor which connection systems are used in your region or oxygencylinders and regulators.

Adapters. In some regions, oxygen-compatible adapters accommodate various regulatorswith other oxygen cylinders. These adapters provide fexibility when one travels to otherareas where dierent cylinders and valves are used. Adapters also let you use regulatorsdesigned or portable oxygen cylinders with nonportable large ones.

Oxygen system adapters are available commercially. To minimize the risk o re andexplosion, they should be oxygen cleaned. Avoid homemade adapters and the use o

scuba regulators with high oxygen concentrations.

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Flow meter. The fow meter, an integral part o thepressure regulator, indicates the oxygen fow ratedelivered through the barbed outlet to theconstant-fow device (nonrebreather mask ororonasal resuscitation mask with supplementaloxygen inlet).

Oxygen fow is measured in liters per minute(lpm). The control valve regulates the fow rateon the regulator, with the fow-rate indicator windowlocated on the ront.

The DAN multiunction regulator is designed to deliver upto 25 lpm. DAN recommends an initial fow rate o 10 lpm whenused with either a nonrebreather mask or oronasal resuscitation mask. The goal o suchsystems is to deliver the highest concentration o oxygen possible to the injured diver.

Oxygen Delivery DevicesDAN demand inhalator valve. DAN OxygenUnits contain a demand inhalator valve (similarto a scuba regulator second stage). When aninjured diver begins breathing through themask and a proper seal between the maskand the injured divers ace is maintained,the injured diver will receive as high aconcentration o oxygen as possible.

With the demand inhalator valve, oxygen fowsonly when the injured diver inhales, and theavailable oxygen supply will oten last muchlonger than with a constant-fow system. Youmay use either an oronasal mask or an oronasalresuscitation mask to t the demand valve tothe injured divers ace.

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Nonrebreather mask.The nonrebreather mask,which may be used toassist a breathing injureddiver, allows an injureddiver to inhale oxygen

rom the reservoir bagpositioned below theoronasal mask. Thenonrebreather maskconsists o a mask withthree nonreturn valves one on either side o themask and one separatingthe mask rom thereservoir bag. Oxygen tubing, located on the side o the mask where the reservoir bag

is attached, connects the mask to the regulator.

During inhalation, oxygen fows through the mask rom the reservoir bag into the injureddivers lungs. The nonreturn valves on the sides o the mask prevent air rom beinginhaled, which would dilute the oxygen.

During exhalation, the one-way valve prevents exhaled air rom fowing back into thebag, but it is released to the outside by the one-way valves on the sides o the mask.

Additionally, during exhalation, the reservoir bag rells with pure oxygen.

The nonrebreather mask is an eective way to deliver a high concentration o inspiredoxygen using the constant-fow eature o the regulator. However, this mask requires alarge supply o oxygen because o the constant fow. Unless the mask completely sealsaround the ace, air will leak past the mask and valves and dilute the oxygen. Thus, thismethod o oxygen delivery is the second choice, ater the demand valve, or a breathinginjured diver.

A nonrebreather mask is recommended or the breathing, injured diver who does nottolerate the demand inhalator valve or when multiple diving injuries require oxygen.

With a good t and proper technique, the nonrebreather mask may deliver inspiredoxygen concentrations up to 80 percent.

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Caution: I the oxygen supply to the nonrebreather mask is interrupted andthe injured diver has a good seal, the injured diver aces some risk o suocating.Thereore, one should never leave an injured diver unattended and should alwaysmonitor breathing while providing emergency oxygen frst aid using a nonrebreathermask. Remove any mask beore turning o the gas supply.

Several other oxygen delivery devices, such as the partial rebreather mask, the simpleace mask and the nasal cannula, are available. Since these devices do not deliversucient percentages o oxygen or require additional training, they are notdiscussed in this course.

Bag valve mask (BVM). The BVM is a sel-infating bag that aids rescuers in providingventilations to a non-breathing or inadequately breathing injured diver. It is connectedto a mask by means o a mechanism with several one-way valves. When the bag iscompressed, air or oxygen is directed through the mask into the injured divers lungs.

The BVM can also be connected to an advanced airway device such as an endotrachealtube used by EMS personnel.

These devices are intended or ventilating nonbreathing or inadequately breathinginjured divers in situations where physical contact is not desired. BVMs are also a goodchoice whentwo rescuers areavailable as it isless atiguing thanproviding rescue

breaths. SinceBVMs ventilatewith air, theyprovide oxygenat concentrationso 21 percent,comparedwith the 16-17percent deliveredthrough rescue

breathing. BVMscan provide muchhigher oxygen

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concentrations i connected to an oxygen cylinder. The concentrations o oxygen aresubstantially reduced when the mask seal is poor. The bag and the mask are available insizes suitable or adults, children and inants. Most adult sel-infating bags have a volumeo 1600 mL. A system or an adult should never be used on a child since the bag canoverexpand a childs lungs. In addition to having a smaller bag, some systems or childreninclude a system or preventing lung overexpansion.

Note: When providing emergency oxygen with a BVM, it is recommendedthat a tidal volume o 400-600 mL be given or 1 second until the chestrises. These smaller tidal volumes are eective or maintaining adequatearterial oxygen saturation, provided that supplemental oxygen is deliveredto the device. These volumes will reduce the risk o gastric ination.

Current BVMs incorporate a connection or oxygen and a reserve bag (or tube), which isusually connected to the base o the resuscitation bag. Oxygen passes into both o themevery time the reservoir is compressed.

To ventilate a nonbreathing or inadequately breathing injured diver, rescuers shouldensure that the airway is open and clear while ensuring a good mask seal. Many studieshave clearly shown that the technique applied by a single rescuer in general producesvery poor ventilations, even though the rescuers may be well trained and conduct itperectly. Thereore, it is recommended that the bag-valve unit be used by a minimum otwo trained rescuers to guarantee the optimal ventilation. One manages the airway andkeeps the mask sealed well, and the other compresses the bag.

Note: Achieving a good seal while liting the jaw with one hand and using

the other to compress the bag is difcult as a single rescuer. The injureddivers mouth sometimes stays partially closed beneath the mask, requiringa high ow o gas to counterbalance nasal obstruction. Leaks are difcultto prevent. The problem o potential leaks can be minimized by regularpractice and a good knowledge o the various techniques, such as using theknees to keep the head tilted.

On the other hand, i a good seal is obtained on the injured divers ace, the BVMcan produce enough pressure to expand the stomach and/or damage the lungs.

Hence the earlier recommendation to limit tidal volume to 400-600 ml.Newer versions o the bag valve mask have a stop valve to help prevent overinfation. Itrestricts air fow rom the bag to the injured diver i resistance, such as may be encounteredi the lungs are overlled, is met during ventilations. The stop valve may also be activatedi too much pressure is being used to operate the system. Either way, the stop valve thenprohibits urther air volume rom being administered.

Despite the potential problems, the BVM can be very eective i used by properly trainedrescuers.

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Description and Function of a Typical BVM Device

Even though dierent models o the BVM have diering design details or characteristics,the operating principles are the same. You should become amiliar with the model youuse.

Ventilation bag. This bag is designed toreinfate ater it is compressed. It rells

with air or oxygen through a suctionvalve at the end o the bag. The suctionvalve also unctions as a nonreturn valve,preventing the gas rom escaping rom thebottom o the bag and preventing strainaround the neck o the bag.

Tolerance valve. Depending on themanuacturer, this assembly containstwoone-wayvalves.Therstisthelipvalve,whichopenswhenthegasexitsfromtheventilation bag and closes when the gas goes in the opposite direction. This allows thegas contained in the ventilation bag to be directed toward the injured diver and preventsthe expired gas rom reentering the bag. The expired gas is directed rom the assemblythrough a separate membrane or through the lip valve, which rises to allow the gas to bedispersed. This membrane also prevents the air rom returning to the injured diver.

Oxygen reserve bag. The majority o BVMdevices have a reserve bag o some type. Thereserve bag is designed to collect the oxygen

during the expiration cycle so that it is availableor the inspiration cycle.

The BVM should include a system orpreventing excess pressure in the systemand/or in the reserve bag caused by theintroduction o unused gas. Some systemshave slits in the reserve bag that open underpressure and allow excess gas to escape. Other devices use an outlet valve or a membrane.

In addition, the BVM requires an inlet that allows a certain amount o air to reenter whenthe reserve bag is used i there is insucient gas to allow the ventilation bag to rell.

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Ventilation bag

Oxygen reserve bag

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Manually Triggered Ventilators

The manually triggered ventilator,also known as a fow-restrictedoxygen-powered resuscitator, is adual unction regulator. It allowsthe rescuer to provide emergency

oxygen to a nonbreathing orinadequately breathing injured diverwith optimal oxygen levels. Theuser can start or stop the oxygenfow immediately by activating abutton similar to the purge buttono a scuba regulator.

It can also unction as a demand valve that can deliver maximum oxygen concentrationsto the breathing diver and minimizes the gas waste.

Lower tidal volumes are recommended with manuallytriggered ventilators. These smaller tidal volumes are eectiveor maintaining adequate arterial oxygen saturation and will

reduce the risk o gastric ination. Ventilations are givenover 1 second until the chest rises. Two rescuers are

recommended when using the manually triggeredventilator. One rescuer should maintain the

airway and mask seal, while the secondrescuer activates the ventilator.

Manually triggered ventilators oer several advantages. They deliver higherconcentrations o oxygen than rescue breathing with supplemental oxygen and areless tiring or the rescuers delivering care. The high concentration o oxygen availablecompensates or any loss that arises as a result o a poor mask seal.

Manually triggered ventilators can deliver a fow greater than 40 lpm to a breathing

injured diver, an amount that is signicantly more than what is required to satisy thebreathing requirements o an individual.

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The MTV-100, one model o manually triggered ventilators, automatically reduces thefow rate to 40 lpm, thereby reducing the risk o introducing gas into the stomach andsubsequent regurgitation. This corresponds with current American Heart Associationrecommendations that a lower fow rate be used to reduce complications. To correctsome o the problems that could occur using the rst oxygen-powered ventilators, theMTV-100 is designed to terminate either the fow or the pressure i excessive pressure is

detected in the airways. In addition, a redundant valve was added or use in the eventthat the rst one ailed.

Some older versions o oxygen-powered ventilators exceeded 160 lpm in deliveredoxygen. Previously it was thought that this amount was necessary to ventilate an injureddiver. However, such a high fow rate can very easily cause expansion o the stomach,which can lead to regurgitation and the aspiration o the contents o the stomach.Moreover, a high fow rate can potentially damage the lungs.

Some other units terminate the fow but do not allow the pressure to be released, whichcould impede the injured divers exhalation. When used on an adult, the saety valveshould prevent pulmonary injuries but might not prevent distension o the stomach(which normally occurs when the esophagus pressure is greater than 15-20 cm H2O).To prevent the outward pressure rom exceeding the expected limits, the MTV-100 hasa saety valve. The oxygen fow terminates when this valve detects mounting pressure ogreater than approximately 60 cm H2O.

Some devices can stop providing gas prematurely without alerting the operator. This canhappen when the lungs o the injured diver present resistance or when there is a poorresponse rom the lungs, as can happen when ventilating an individual with asthma or an

injured diver who has experienced a submersion incident. The MTV-100 has an acousticalarm that alerts the operator o excessive levels o pressure in the airways. I the devicedoes not signal an acoustic alarm, the operator may not become aware o the resistanceduring resuscitation, and thereore an obstruction in the airway or an overexpansion othe lungs may not be detected.

As with all oxygen-assisted ventilation techniques, when the oxygen supply is exhausted,these units can no longer be used.

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DAN Oxygen Units

DAN Oxygen Units were specially designed with divers in mind. Each unit is capableo delivering high concentrations o inspired oxygen to injured divers.

Rescue Pak. The Rescue Pak is anaordable and compact oxygensystem, ideal or areas where

emergency medical services existnearby or the distance to the nearestmedical acility is short. It includesthefollowing:

BrassmultifunctionregulatorDemandvalvewithhoseM9oxygencylinder(248liters)Nonrebreathermaskwith

6-oot tubing

OronasalresuscitationmaskTru-Fitsiliconemask DANDive and Travel Medical GuidePelican 1450 waterproo caseOptionalMTV-100withhose

Rescue Pak Extended Care. The Rescue Pak Extended Care, a popular choice amongdivers, is a sel-contained kit that has all the necessary equipment to provide rst aid orbothbreathingandnonbreathinginjureddivers.Itincludesthefollowing:

BrassmultifunctionregulatorDemandvalvewithhoseJumbo-Doxygencylinder

(636 liters)Nonrebreathermaskwith

6-oot tubingOronasalresuscitationmaskTru-Fitsiliconemask DANDive and Travel

Medical Guide

Pelican

1600 waterproo caseOptionalMTV-100withhose

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Dual Rescue Pak Extended Care. DANs dual-cylinder unit is ideal or oshore diving orfordiverswhodesireagreateroxygensupply.Itincludesthefollowing:

BrassmultifunctionregulatorDemandvalvewithhoseTwoJumbo-Doxygencylinders

(636 liters each)

Nonrebreathermaskwith6-oot tubing

OronasalresuscitationmaskTru-Fitsiliconemask DANDive and Travel Medical GuidePelican 1600 waterproo caseOptionalMTV-100withhose

Sot-Sided Oxygen Unit. The DAN Sot-SidedOxygen Unit provides the same components as the RescuePak Extended Care in a compact, water-resistant nyloncase designed exclusively or the unit.

Charter Boat Oxygen Unit. DANs Charter Boat Oxygen Unitallows the use o larger oxygen cylinders, which provideor extended oxygen treatment i required. It includes thefollowing:

Brassmultifunctionregulator withCGA-540connectorDemandvalvewithhoseOronasalresuscitationmaskNonrebreathermaskwithtubingWrenchforCGA-540connectorDANDive and Travel Medical GuidePelican 1400 waterproo case

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First Aid Backpack with Oxygen Option. Not only is this backpack ully stocked withrst aid supplies, it also includes an adjustable padded pouch with Velcro backing,designed to t a standard M9 oxygen cylinder. This is a portable, durable and practicalunit with refective strips and D-rings eatured on the shoulder straps, and the waterproocover is stored in the bottom compartment o the backpack. It includes the ollowingitems:

BrassmultifunctionregulatorM9cylinder(248liters)DemandvalvewithhoseOronasalresuscitationmaskNonrebreathermaskwith

6-oot tubingTru-Fitsiliconemask DANDive and Travel

Medical Guide

DivesafetyslatesNitrileglovesMedications/ToolsPack StopBleeding/ShockPackWounds(Cuts)CarePackFractures/Sprain/StrainPack

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1. Oxygen delivery systems are comprised

o which o the ollowing? (Mark all that

apply.)

a. Oxygen cylinderb. Pressure-reducing regulator

c. Oxygen hose

d. Face mask

2. Name two considerations when

choosing an oxygen cylinder.

___________________________

___________________________

3. A multiunction regulator is preerred in

emergency oxygen or scuba divinginjuries because it can provide emergency

oxygen to two injured divers at the same

time.

a. True b. False

4. An oxygen cylinder should be switched

during care when the pressure drops

below 200 psi i another cylinder is

available or, i there is not another

cylinder available, use the cylinder

until it is emptya. True b. False

5. Oxygen cylinders

Documents

2012 EO2 Student HB v1.0